Low-water alarm for steam-boilers



J. A. LEAVITT.

LOW WATER ALARM FOR STEAM BOILERS.

APPLICATION FILED JAN. 13. 1920.

l Invenor James Leavitt JAI'IES ALLEN LEAVITT, 0F HERMOSA. BEACH,CALIFORNIA.

LGW'".UATER ALARM FOR STEAM-BOILEES.

Speetcation of Letters IEatent. i

Patented Jan. at, 1921.

Application filed January 13, 1920. Serial No. 351,15e.

T 0 @ZZ whom it may concer/a Be it lnown that l, latins A. LnAvrr'r, acitizen of the United States, residing at Hermosa Beach, in the countyof Los Angeles and State of California, have invented certain new anduseful improvements in Low-Vlater Alarms for Steam-Boilers; and l dohereby declare the following to be a full, clear, and exact descriptionof the invention, such as will enable others skilled in the art to whichit appertains to make and use the same, reference being had to theaccompanying drawings, and to the letters and figures of referencemarked thereon, which form a part of this specification.

This invention relates to new and useful improvements in low water alarmapparatus for steam boilers, and comprises means whereby, when the waterwithin the boiler lowers to a dangerous point, means is actuated forautomatically sounding an alarm and shutting off the supply of fuelleading to the burners of the boiler.

rl`he invention, more particularly consists of a plug mounted in anopening of the crown sheet of a boiler, containing a fusible material,against which a spring pressed rod bears which, when the tempera-ture ofthe boiler is sufficient to cause the metal to fuse, will be actuated toremove any scale which might prevent the fusible metal from openingpassageways through which steam is adapted to pass, for the purpose ofsounding the signal and shutting ofi the supply of fuel to the burners.

My invention comprises various other details of construction,combination and arrangement of parts which will be hereinafter fullydescribed, shown in the accompanying drawings and then specificallydefined in the appended claim.

lf illustrate my invention inthe accompanying drawings which, with theletters of reference marked thereon, form a part of this application,and in which:

Figure l is a central vertical sectional view through a portion of theboiler, showing the application of my invention thereto.

Fig. 2 is an enlarged detail sectional view through the fusible plug,pipe and connections therewith, and illustrating in elevation a springactuated plunger for removing any scale which might form over the lowersurlface of the top section of the fusible plug, anc

Fig. 3 is an enlarged detail in section of a steam 'actuated valve.

Reference now being had to the details of the drawings by letter:

il, designates a steam boiler, and B a crown sheet therein. A plug N ismounted in a threaded opening in the crown sheet, and M designates apipe having threaded connection with an aperture in the top of the plug,and extending upward and passing through an opening in the top of theboiler. 'A slight distance above the top of the boiler said pipe isconnected to a cage C with which it has threaded connection. Said plugis provided with a series of circumferential openings O and in theopening in said plug intermediate the lower end of the pipe M and theupper marginal edge of said openings O is a filling of fusible materialP.

Said plug has a central opening Q leading downward from a locationopposite the lower marginal edges of the openings O and connects withbranching ducts Q2 leading through the extreme lower end of the plug,and which opening and branching ducts are adapted to be filled with afusible material Q3.

A rod L is positioned within the pipe M and has a pointed end L restingagainst the upper surface of said fusible filling P. and its upper endis provided with a shoulder K against which the lower end of a coiledspring d bears, its upper end lbeing engaged by a disk H engaged by anadjusting screw F, mounted in the cap Gr which has threaded connectionwith the cage C. A pipe D is connected to and communicates with theinterior of the cage C, and E is a whistle which is connected to thepipe D at any suitable location, and which pipe communicates with acasing S', which in turn is connected to a valve casing R containing avalve T, the stem of which is connected to a follower S, against which aspring S2 bears, and tends to normally hold the valve raised from itsseat.

A pipe U communicates between the valve casing R and the burner V.

ln operation, when the apparatus is adjusted for use, the parts assumethe position shown in Fig. 2 of the drawings, in which which closescommunication between the interior of the boiler and the pipe M, thevalve T being unseated to permit oil to flow to the burner, whereby heatmay be generated by the burning of fuel to produce steam within theboiler. In the event of the water in the boiler lowering to a dangerouspoint, and when the temperature therein increases sufficiently to fusethe filling material P of fusible metal in the plug N, and upon whichthe point of the rod L rests, the metal, as it fuses, will run throughthe openings O in the plug and communication will be afforded betweenthe boiler and the interior of the pipe M, and the steam passing throughthe pipes M and D will cause the whistle E to be sounded and the valve Tto seat, which latter operation will shut off the supply of oil to theburner V.

In the event of any scale forming on the lower surface of the fusiblefilling material P, the pointed end L of the rod will break the same asthe spring J, which is normally under tension, will force said roddownward, removing the scale and permitting the y free passage of thesteam into the pipe if. As the fusible material in the openingand theducts in the lower portion of the plug melts, it will run through theducts to the furnace beneath, and allow steam and water to flow fromboiler to lire-box.

crown sheet, a plug mounted in an opening in the crown sheet and havingcircumferential openings therein and also downward extending openings inthe lower part thereof and communicating with the fire box, a filler offusible material in the upper end of the plug which communicates withsaid circumferential openings, fusible material filling said downwardextending openings, a pipe connected to said plug and passing through anopening in the boiler, a cage connected to the top of said pipe, a rodmounted within said pipe and having its lower end pointed and adapted torest upon the upper surface of the fusible material in the upper portionof said plug, said rod having a shoulder near its upper end, a screwactuated disk mounted in said cage, a coiled spring interposed betweensaid shoulder and disk, a pipe leading from said cage and provided witha whistle, a fuel pipe disposed beneath the lower end of said pipe whichleads from the cage, and a normally open valve in said fuel pipe,closable by pressure of steam when admitted to said pipe leading fromthe cage. l

In testimony whereof I hereunto aflix my signature.

JAMES ALLEN LEAVITT.

